Sennheiser replacement cables

I believe that the 580 & 600 cables are terminated with a mini-plug [1/8"], while the 650 cable is terminated with the standard 1/4" plug.

Not correct, they are interchangeable and they all have a 1/4" plug.

The 650 cable is by far the best of the two, and cheaper to boot.. A no-brainer. :)

All after-market cables are better than the Sennheiser one though, so you might want to check these out before doing anything.

My fairly new Sennheiser 600's have a 1/8" mini plug and came with an adapter to 1/4".

Really Sfar? They're all 1/4" where I live. :) Perhaps they can be ordered with either, that would explain things!

In any case, the three phones can all use the same cables since they have the same connectors. The 600s sound slightly better with the 650 stock cable, so that could be a worthwhile upgrade. However I still recommend getting something better, there's plenty of good ones out there. :)